The present invention relates to an electrically powered foldable outer rearview mirror for a motor vehicle.
An electrically powered foldable outer rearview mirror for a motor vehicle is known comprising a mirror body rotatably supported on a shaft mounted on a base, an electric drive means and speed reduction gear mechanism mounted on a frame of the mirror body, and a clutch gear mounted on the shaft so as to be fixed to the shaft when the mirror is electrically powered and to be free of the shaft when the mirror is forcibly rotated. The erected state and the folded state of the mirror body are maintained by engaging recesses formed on a shaft base portion with steel balls which are arranged on the frame root portion or on the undersurface of the clutch gear.
In electrically powered foldable outer rearview mirrors as described hereinbefore, as disclosed by Japanese Published Patent No. Hei 3-16841, several steel balls are provided on a frame (or a bracket) root portion in the mirror body, while first and second recesses are provided in the shaft base portion according to the erected mirror position and folded mirror position. The steel balls are engaged in the first and second recesses in the respective mirror erected and folded mirror position. When the mirror body is rotated, each steel ball is rotated on a sliding surface of the shaft base extending through the recesses. Also in another system disclosed in Published Japanese Utility Model Registration Application No. Hei 3-69552, the clutch gear is provided between the frame root portion and the shaft base portion and several steel balls are arranged between the upper surface of the clutch gear and the frame root portion, and between the lower surface of the clutch gear and the shaft base portion, respectively.
In a conventional system for automatically folding the outer rearview mirror, however, chattering of the mirror surface occurs, which is caused by a vertical movement of the mirror body during rotation because:
1. the clutch gear or a stopper plate is arranged between the shaft and the frame and the positioning of the mirror and the shock avoidance properties are determined by the steel balls so that the system does not have good stability and chattering is easily caused by inaccurate engagement of the parts of the operating mechanism during vehicle operation; PA1 2. the clutch gear or the stopper plate is provided between the shaft and the frame so that the system is not waterproof and dustproof; PA1 3. the frame moves vertically when the mirror is electrically rotated to erect and fold the mirror body and the mirror body can be forcibly rotated; and PA1 4. in the system described by Published Japanese Patent Application No. Hei 3-16841, both clutches are simultaneously released at the time the mirror is forcibly rotated so that the gear teeth bear a much heavier load.